Search these forums as this had been discussed ad nauseum.
In summary, here are the two main suggestions:
1) purchase a high quality two-channel amplifier. Use the B&K's preouts to this new amp and connect the new amp to your speakers.
Benefits: your B&K will not have to amplify the main speakers and you can easily find a dedicated amp that will beat most receivers.
2) buy an integrated and take the B&K completely out of the loop when listening to stereo. Many integrateds have a HT pass-through feature but it's not 100% necessary.
Benefits: a dedicated two-channel integrated will most likely have superior performance (on the pre- and power- sides) over a receiver.
Check out my system to see how I did it and search the archives on the 'gon.
Good luck!